Even Joe Girardi said Thursday that it's "kind of strange" for the Yankees and Mets to be playing the Subway Series this early in the season.

The Mets visit Yankee Stadium Friday night with the best record in baseball (13-3) and an 11-game winning streak. The Yankees (9-7) have a three-game winning streak after a 7-3 road trip. "They're as hot as can be, so it should be great . . . a great atmosphere," Girardi said.

Here are five story lines to watch for this weekend's series. The teams will meet again Sept 18-20 at Citi Field.

The Mets just completed a 10-0 homestand despite losing David Wright, Travis d'Arnaud and Jerry Blevins to injuries. They have displayed excellent starting pitching, clutch hitting and reliable relief pitching, with Jeurys Familia taking a stranglehold on the closer's job after the suspension of Jenrry Mejia.

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The good feelings started in spring training when the Mets went 19-12. Scoff if you like, but everyone connected with the team thinks a winning culture began to take root in Port St. Lucie.

ARE YANKEES MORE THAN AN A-ROD SIDESHOW?Alex Rodriguez has proved he still can hit. It's the rest of the lineup that has to be questioned. Carlos Beltran, dropped to fifth, has shown signs of improvement recently but is losing playing time to another former Met, Chris Young. Brian McCann has one home run. Jacoby Ellsbury only recently picked up his first RBI. Stephen Drew (.178) and Didi Gregorius (.200) are performing down to expectations. Against the Mets' starting pitching, this could be a recipe for disaster.

Rodriguez is two homers shy of tying Willie Mays for fourth on the all-time home run list and triggering a $6-million contract bonus the Yankees reportedly are not going to pay because they believe A-Rod's PED past has tainted the chase.

If A-Rod hits Nos. 659 and 660 against the Mets, it will be impossible for anyone to ignore. Except, apparently, the Yankees, who have scrubbed any reference to the upcoming milestone from their all-encompassing universe.

"It's always fun to play the Mets. That's one of the things I missed most while I was gone for such a long time," A-Rod said. "It gives us an opportunity to celebrate a great game in front of all New Yorkers . . . It should be rocking."

BRINGING QUEENS

TO THE BRONX

There's a pretty decent chance Yankee Stadium will sound more like Citi Field this weekend, especially if the Mets get off to early leads. A dedicated group of Mets fans has snapped up tickets and is planning to drown out Yankees fans with chants of "Let's Go, Mets!" (But no roll calls from Mets fans, please -- that's a Yankees thing.)

It won't affect the action on the field, but the preseason story line of "Will the Mets take back New York from the Yankees?" could get a boost in Flushing's favor if Yankees fans sit on their hands and Mets fans are wearing out their lungs this weekend.

"I know there's a lot of Mets pride going on and I know there's a lot of Yankees stuff for years and years, so I look forward to the environment," Chase Headley said. "I think it's good. Probably nobody likes to hear that as a Yankees fan, but I think it's good when both teams are good. It's good for baseball."

SEE YOU IN SEPTEMBER

As we mentioned, the teams meet again in mid-September. The Mets' rip-roaring start makes it more likely they'll be fighting for a playoff spot in five months than it seemed when the season began.

The Yankees also have postseason aspirations. It'll probably be "strange" again to see the teams playing so late in the season, but how much fun will it be if both are playing for something as the leaves start to turn?